Actuator and image pickup device

ABSTRACT

An actuator has a magnet moved together with a moving lens frame, an SMA wire capable of extending and contracting in a moving direction I of the moving lens frame with execution or non-execution of energization thereof, a fixing member made of a magnetic material attached to a distal end of the SMA wire, a pressing spring which urges the fixing member toward the magnet along the moving direction I, and a stopper member and a stopper portion which limits the movement of the magnet along the moving direction I at a first position or a second position.

This application claims benefit of Japanese Applications No. 2007-241489filed in Japan on Sep. 18, 2007 and No. 2007-252430 filed in Japan onSep. 27, 2007, the contents of which are incorporated by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an actuator configured to move a movingportion with expansion/contraction of a shape memory alloy and to animage pickup apparatus used in a medical apparatus such as an endoscopeand capable of changing optical performance by the actuator.

2. Description of Related Art

In recent years, endoscopes are widely used in the medical andindustrial fields. Endoscopes have an elongated insertion portioninserted in a tube to enable observation in the tube.

An image pickup apparatus including an objective optical system formedof a plurality of objective lens groups for observing the interior of atube, and a solid-image pickup device or the like such as a CCD isgenerally provided in a distal end portion at a distal end side in theinsertion direction in an insertion portion of an endoscope, e.g., anelectronic endoscope, which is configured to pick up an image of anobserved portion in a tube formed by the objective optical system.

A zoom endoscope is well known in which at least one lens in a pluralityof objective lens groups in an objective optical system is provided as amoving lens capable of moving in an optical axis direction of theobjective optical system, and in which optical characteristics includingthe depth of focus of the objective optical system on an observedportion, the observation magnification and the angle of view can bechanged by moving the moving lens in the optical axis direction. Byobservation using the zoom endoscope in a case where the zoom endoscopeis, for example, an endoscope for medical use, mucous membranes, thestructure of capillaries, etc., at an observed position in a body cavitycan be observed.

Various mechanisms have been proposed as a mechanism for moving in anoptical axis direction a moving lens provided as a moving member asdescribed above. For example, Japanese Patent Application Laid-OpenPublication No. 2004-129950 discloses a technique to move a moving lensin an optical axis direction by extending and contracting in the opticalaxis direction a shape memory alloy (hereinafter referred to as SMA)wire extending in the optical axis direction and having its one endfixed to a projection formed integrally on a moving lens frame in whichthe moving lens is provided. To extend or contract the SMA wire, the SMAwire is set in an energized state or in a non-energized state. That is,the publication discloses a technique to move a moving lens in anoptical axis direction by using an actuator having an SMA wire.

Japanese Patent Application Laid-Open Publication No. 2005-003867discloses a technique to move a moving lens in an optical axis directionby using repellency between a north pole of a drive magnet and a northpole of a follower magnet or repellency between a south pole of thedrive magnet and a south pole of the follower magnet. The followermagnet is provided along an optical axis direction on a moving magnetholder fixed on a moving lens barrel holding a moving lens. The drivemagnet is held on a drive magnet holder movable in a clockwise directionand in a counterclockwise direction. The drive magnet holder is providedon the outer peripheral side of the moving lens in a diametric directionof the moving lens than the driven magnet. That is, the publicationdiscloses a technique to move a moving lens in an optical axis directionby using an actuator having a follower magnet and a drive magnet.

Other techniques to move a lens moving member in an optical axisdirection by magnetic action have been disclosed. For example, JapanesePatent Application Laid-Open Publication No. 2005-227705 discloses onefor a lens drive apparatus. Further, Japanese Patent ApplicationLaid-Open Publication No. 2006-276798 discloses a technique to open andclose a shutter and a diaphragm by magnetic action in an image pickupapparatus.

Among configurations including a lens movable by changing the opticalfocal position, the lens drive apparatus described in Japanese PatentApplication Laid-Open Publication No. 2005-227705 or the image pickupapparatus described in Japanese Patent Application Laid-Open PublicationNo. 2006-276798 is provided with a variable diaphragm for adjusting theoptimum brightness, i.e., the amount of light in the optical system.

SUMMARY OF THE INVENTION

An actuator according to the present invention has a magnet movedtogether with a moving portion, a shape memory alloy wire capable ofextending and contracting in a direction of movement of the movingportion with execution or non-execution of energization thereof, afixing member made of a magnetic material attached to a distal end ofthe shape memory alloy wire, a spring which urges the fixing membertoward the magnet along the direction of movement, and a stopper portionwhich limits the movement of the magnet along the direction of movementat a set position.

A first image pickup apparatus according to the present inventionincludes an actuator having a magnet moved together with a movingportion, a shape memory alloy wire capable of extending and contractingin a direction of movement of the moving portion with execution ornon-execution of energization thereof, a fixing member attached to adistal end of the shape memory alloy wire, a spring which urges thefixing member toward the magnet along the direction of movement, and astopper portion which limits the movement of the magnet along thedirection of movement at a set position. In the first image pickupapparatus, the moving portion is a movable lens frame holding a movablelens, and provided in a movable lens unit having magnetic member, and afixed lens frame in which a plurality of objective optical systems aredisposed, and in which the movable lens frame is held so as to be ableto advance and retract in a shooting optical axis direction is provided,and the actuator which advances and retracts the magnetic member of themovable lens frame by magnetic force from the outside of the fixed lensframe.

A second image pickup apparatus according to the present invention has amovable lens unit having a movable lens frame holding a movable lens,and a magnetic member, a fixed lens frame in which a plurality ofobjective optical systems are disposed, and in which the movable lensframe is held so as to be able to advance and retract in a shootingoptical axis direction, a diaphragm unit which adjusts the amount ofshooting light by moving a diaphragm blade formed of a magneticmaterial, and a magnet which moves the diaphragm blade by magnetic forceaccording to the advancement and retraction of the movable lens frame.

The above and other objects, features and advantages of the inventionwill become more clearly understood from the following descriptionreferring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view of a distal end portion of anendoscope having an actuator representing a first embodiment;

FIG. 2 is a partial sectional view of a distal end portion of theendoscope taken along line II-II in FIG. 1;

FIG. 3 is a partial sectional view of a distal end portion of theendoscope taken along line III-III of FIG. 1;

FIG. 4 is a partial sectional view of a distal end portion of theendoscope, showing a state in which a magnet shown in FIG. 1 is broughtinto abutment on a stopper portion of a second lens frame;

FIG. 5 is a partial sectional view of the distal end portion of theendoscope, showing a state in which a fixing member is moved apart fromthe magnet when the magnet shown in FIG. 4 is in abutment on the stopperportion of the second lens frame;

FIG. 6 is a graph showing, as a hysteresis curve, changes in the amountof deformation with respect to the temperature of an SMA wire shown inFIG. 1;

FIG. 7 is a partial sectional view of a distal end portion of anendoscope having an actuator representing a second embodiment;

FIG. 8 is a partial sectional view of the distal end portion of theendoscope, showing a state in which a magnet shown in FIG. 7 is broughtinto abutment on a stopper portion of a second lens frame;

FIG. 9 is a partial sectional view of the distal end portion of theendoscope, showing a state in which a fixing member is moved apart fromthe magnet when the magnet shown in FIG. 7 is in abutment on the stopperportion of the second lens frame;

FIG. 10 is a partial sectional view of a distal end portion of anendoscope having an actuator representing a third embodiment;

FIG. 11 is a partial sectional view of the distal end portion of theendoscope, showing a state in which a magnet shown in FIG. 10 isattached to a rear magnet in a second lens frame;

FIG. 12 is a partial sectional view of a distal end portion of anendoscope having an actuator representing a modified example of thepresent embodiment in which a stopper member is provided on the stopperportion shown in FIG. 1;

FIG. 13 is a diagram showing a configuration of a rigid electronicendoscope according to a fourth embodiment;

FIG. 14 is a sectional view of an image pickup apparatus disposed in adistal end portion of the rigid electronic endoscope;

FIG. 15 is a sectional view taken along line XV-XV in FIG. 14;

FIG. 16 is an exploded perspective view of a diaphragm unit;

FIG. 17 is a front view of the diaphragm unit;

FIG. 18 is a sectional view taken along line XVIII-XVIII in FIG. 17;

FIG. 19 is a sectional view showing a state in which a moving lens unitis positioned rearward;

FIG. 20 is a sectional view taken along line XX-XX in FIG. 19;

FIG. 21 is a sectional view showing a state in which the moving lensunit is positioned forward;

FIG. 22 is a sectional view taken along line XXII-XXII in FIG. 21;

FIG. 23 is a partial sectional view showing a configuration of an imagepickup apparatus according to a fifth embodiment;

FIG. 24 is a sectional view showing a state in which a movable lens unitis positioned rearward;

FIG. 25 is a sectional view taken along line XXV-XXV in FIG. 24;

FIG. 26 is a sectional view showing a state in which the movable lensunit is positioned forward;

FIG. 27 is a sectional view taken along line XXVII-XXVII in FIG. 26;

FIG. 28 is a front view of the configuration of a diaphragm unitaccording to a first modified example;

FIG. 29 is a sectional view taken along line XXIX-XXIX in FIG. 28;

FIG. 30 is a front view of a configuration of a diaphragm bladeaccording to a second modified example; and

FIG. 31 is a front view of a configuration of a diaphragm bladeaccording to a third modified example.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention will be described with reference tothe drawings. In the embodiments described below, an actuator isdescribed as one used in an endoscope.

First Embodiment

FIG. 1 is a partial sectional view of a distal end portion of anendoscope having an actuator according to the present embodiment; FIG. 2is a partial sectional view of a distal end portion of the endoscopetaken along line II-II in FIG. 1; and FIG. 3 is a partial sectional viewof a distal end portion of the endoscope taken along line III-III ofFIG. 1.

As shown in FIG. 1, a substantially cylindrical distal end holder 4 isprovided in a distal end portion 1 of the endoscope along an insertiondirection S of the endoscope, and a plurality of through holes areformed in the distal end holder 4 along an insertion direction S.

As shown in FIG. 3, a channel 2 for insertion of a treatment instrument,which is also used as a suction tube channel, a cleaning nozzle 41 forcleaning an objective lens by jetting a fluid to the lens, anillumination optical system 42 for illuminating a subject portion, whichcomprises two illumination optical systems in the present embodiment,angling wires 43, an image pickup apparatus 50, or the like arerespectively provided in the plurality of through holes formed in thedistal end holder 4. The channel 2, the cleaning nozzle 41, theillumination optical systems 42 and the angling wire 43 have well-knownconfigurations and functions, which, therefore, will not be described inthe present embodiment.

A configuration of the image pickup apparatus 50 provided in the throughhole in the distal end holder 4 will next be described. The image pickupapparatus 50 has a well-known configuration, which therefore will onlybe outlined.

In the image pickup apparatus 50, a second lens frame 32, which is anonmagnetic member constituted of a nonmagnetic material, is fittedaround an outer periphery of a first lens frame 5 holding an objectivelens group 3 constituted of a plurality of objective lenses at anintermediate position on the first lens frame 5 along an insertiondirection S.

A stopper member 35, which defines a position to which a magnet 8described below is moved toward the distal end side in the insertiondirection S is fitted around an outer periphery of the second lens frame32 at a distal end side of the same in the insertion direction S. Thatis, the stopper member 35 defines a position to which a moving lensframe 6 described below, more particularly a moving lens 7 is movedtoward the distal end side in a moving direction I. More specifically,the moving lens 7 is defined to a position corresponding to a 1×1magnification.

Further, the moving lens frame 6, which is a moving portion holding themoving lens 7, is provided on an inner periphery of the second lensframe 32 so as to be movable in the moving direction I along theinsertion direction S in an enclosed space 33 in the second lens frame32.

In the image pickup apparatus 50, a known solid-state image pickupelement 10, an electronic circuit board 11, a signal cable 12 and othercomponents are further provided at the rear of the moving lens 7 in theinsertion direction S. A stopper portion 31 formed of a stepped portionis formed in an outer periphery of the second lens frame 32 at anintermediate position in the insertion direction S at the lower side asviewed in FIG. 1.

The stopper portion 31 defies a position to which the magnet 8 is movedtoward a rear end side in the insertion direction S. That is, thestopper portion 31 defines a position to which the moving lens frame 6,more particularly the moving lens 7 is moved toward a rear end side inthe moving direction I. More specifically, the moving lens 7 is definedat a position corresponding to the maximum magnification.

In the through hole which is formed in the distal end holder 4 and inwhich the image pickup apparatus 50 is provided, an actuator 20 isprovided together with the image pickup apparatus 50.

As shown in FIG. 2, an essential portion of the actuator 20 isconfigured, along an outer periphery of the moving lens frame 6 at thelower side as viewed in FIG. 1, of the magnet 8, an SMA wire 14, afixing member 9, a pressing spring 16, the stopper portion 31 formed inthe above-described second lens frame 32, and the stopper member 35, themagnet 8 being provided in the lower portion of FIG. 1, via the secondlens frame 32.

The magnet 8, the SMA wire 14, the fixing member 9, the pressing spring16, the stopper portion 31 and the stopper member 35 are disposed bybeing arranged in a straight line along the moving direction I, as shownin FIG. 1.

The magnet 8 moves by magnetic force in the moving direction I togetherwith the moving lens frame 6. The SMA wire 14 extends and contracts inthe moving direction I of the moving lens frame 6 withenergization/non-energization of the SMA wire 14. More specifically, theSMA wire 14 is a wire constituted of SMA, having a diameter of severalten micros, contracting in the moving direction I when heated, andextending in the moving direction I when cooled.

The SMA wire 14 is inserted in a guide pipe 15 and in a first insulatingtube 17 provided along the insertion direction S. The first insulatingtube 17 is fixed by being fitted at its distal end side in an innerperiphery of the guide pipe 15 at the proximal end side in the insertiondirection S.

One end of the SMA wire 14 is swaged in a first swaged portion 25 formedof a cylindrical metal ring. A drive cable 26 through which a current issupplied to the SMA wire is electrically connected to the first swagedportion 25 by soldering. The connection between the first swaged portion25 and the drive cable 26 is reinforced on the periphery thereof by anadhesive or the like, not shown in the figure.

The position in which the first swaged portion 25 is mounted is set at aposition on the distal end side in the insertion direction S of aflexible tube portion not shown in the figure, provided continuouslywith a bending portion of the endoscope on the proximal end side.

The SMA wire 14 is inserted at an intermediate position in a grooveformed in the fixing member 9 but not shown in the figure and is bent soas to be turned back along the insertion direction S. The portion of theSMA wire 14 inserted in the groove in the fixing member 9 is bonded andfixed to the fixing member 9 by a ball 13.

The other end of the SMA wire 14 turned back is swaged in a secondswaged portion 29 formed of a cylindrical metal ring. A GND cable 28 iselectrically connected to the second waged portion 29 by soldering.

An anchor 19 in ring form is fitted around portions of outer peripheriesof the first insulating tube 17 and the GND cable 28 (the anchor 19provided on the portion of the outer periphery of the GND cable 28 isnot shown in FIG. 2) and are bonded and fixed to the portions of theouter peripheries.

A protective tube 22 is attached to the first insulating tube 17 and theGND cable 28 so as to cover the anchor 19 and the first insulating tube17, as shown in FIG. 1. The protective tube 22 is fixed at its distalend in the insertion direction S to the first insulating tube 17 bybinding with a string 18 such as an artificial silkworm gut.

The fixing member 9 is attached to the distal end of the SMA wire 14 inthe moving direction I and is constituted of a magnetic material.

The pressing spring 16 is provided between the first insulating tube 17and the fixing member 9 in the guide pipe 15. The pressing spring 16urges the fixing member 9 toward the magnet 8 along the moving directionI, so that the fixing member 9 constituted of a magnetic material can beattracted and attached to the magnet 8 by magnetic force.

The operation of the present embodiment thus configured will bedescribed with reference to FIGS. 4 to 6 as well as to FIGS. 1 to 3described above. FIG. 4 is a partial sectional view of a distal endportion of the endoscope showing a state in which the magnet shown inFIG. 1 is brought into abutment on the stopper portion of the secondlens frame. FIG. 5 is a partial sectional view of the distal end portionof the endoscope showing a state in which the fixing member is movedapart from the magnet when the magnet in FIG. 4 is in abutment on thestopper portion of the second lens frame. FIG. 6 is a graph showing, asa hysteresis curve, changes in the amount of distortion with respect tothe temperature of the SMA wire shown in FIG. 1.

First, when the moving lens 7 is moved to a first position Ia which is aset position corresponding to 1×1 magnification, the SMA wire 14 of theactuator 20 is set in a non-energized state. As a result, the SMA wire14 extends toward the distal end side in the moving direction I, and thefixing member 9 is pressed by the pressing spring 16 toward the distalend side in the moving direction I to press the magnet 8 against thestopper member 35 in a state of being attached to the magnet 8 bymagnetic force, as shown in FIG. 1. As a result, the moving positions ofthe moving lens frame 6 and the moving lens 7 are fixed at thedistal-most end side of the moving direction I, i.e., the first positionIa corresponding to 1×1 magnification in the moving range from Ia to Ib.The amount of deformation of the SMA wire 14 at this time is representedby εa and the temperature at this time is represented by t1. Also, atthis time, the magnet 8 and the stopper portion 31 are separate fromeach other.

Next, when the moving lens 7 is moved to a second position Ibcorresponding to the maximum magnification, that is, the moving lens 7is moved to the rear end side in the moving direction I, a current issupplied from a power supply not shown in the figure to the drive cable26 in the actuator 20.

Thereafter, the current flows through the drive cable 26, the firstswaged portion 25, the SMA wire 14, the second swaged portion 29 and theGND cable 28, and the SMA wire 14 produces heat and contracts so thatthe amount of deformation changes from εa to εb with respect to thetemperature of the SMA wire 14 from t1 to t2, as indicated by a curve(a) in FIG. 6.

As a result, the fixing member 9 to which the SMA wire 14 is fixed ismoved rearward in the moving direction I and the magnet 8 that hasattached to the fixing member 9 by magnetic force is also moved rearwardin the moving direction I while attaching to the fixing member 9.Further, the moving lens frame 6 and the moving lens 7 are also movedrearward in the moving direction I in the enclosed space 33 by themagnetic force of the magnet 8.

The magnet 8 is then brought into abutment on the stopper portion 31 ofthe second lens frame 32, as shown in FIG. 4. The amount of deformationof the SMA wire 14 at this time is represented by εb and the temperatureat this time is represented by t2. The stopper portion 31 stops themagnet 8 from moving rearward in the moving direction I from the secondposition Ib, which is a set position at which it abuts on the stopperportion 31, even when the SMA wire 14 contracts further. That is, themoving lens frame 6 and the moving lens 7 that have been moved rearwardin the moving direction I by the magnetic force of the magnet 8 aredefined in the rearmost position in the moving range of the moving lensframe 6 and the moving lens 7. In other words, the moving lens 7 ismoved to the second position Ib corresponding to the maximummagnification to fix the moving position. At this time, the magnet 8 andthe stopper member 35 are separate from each other.

When the SMA wire 14 contracts further so that the amount of deformationwith respect to the temperature of the SMA wire 14 from t2 to t3 is εbto εc as indicated by the curve (a) in FIG. 6 in the state where themagnet 8 is in abutment on the stopper portion 31 at the second positionIb, the fixing member 9 is separated from the magnet 8 and movedrearward in the moving direction I to a third position Ic for example,as shown in FIG. 5.

When the fixing member 9 is separated from the magnet 8, the magnet 8remains in abutment on the stopper portion 31, and the moving lens frame6 and the moving lens 7 remain at the second position Ib.

Also, when the fixing member 9 is separated from the magnet 8, that is,the SMA wire 14 does not pull the magnet 8 by contraction in the statewhere the magnet 8 is in abutment on the stopper portion 31, noexcessive load is applied to the SMA wire 14.

The reason for the effect of maintaining the magnet 8 in abutment on thestopper portion 31 even when the fixing member 9 is separated from themagnet 8 is that magnetic force acts between the fixing member 9 and themagnet 8 even after the fixing member 9 has been separated from themagnet 8 if the separation distance in the moving direction I is notlarge, and that the moving lens frame 6 abuts on the inner periphery ofthe second lens frame 32 with frictional force due to the magnetic forcebetween the magnet 8 and the moving lens frame 6.

It can be understood that if the amount of deformation of the SMA wire14 at the third position Ic is εc and the temperature of the SMA wire 14is t3, the amount of deformation (from εb to εc) with respect to a unittemperature (from t2 to t3) in the case of deformation from the secondposition Ib to the third position Ic after bringing the magnet 8 intoabutment on the stopper portion 31 does not differ largely from theamount of deformation (from εa to εb) with respect to the unittemperature from the first position Ia to the second position Ib (fromt1 to t2), as indicated by the curve (a) in FIG. 6.

It can also be understood that when the SMA wire 14 contracts beyond thethird position Ic, the amount of deformation with respect to the unittemperature is reduced relative to the amount of deformation (from εa toεc) from the first position Ia to the third position Ic is small or iszero, as indicated by the curve (a) in FIG. 6.

That is, in the present embodiment, the SMA wire 14 is contracted in therange from εa to εc in which the amount of deformation of the SMA wire14 is substantially constant with respect to the unit temperature in thetemperature range from t1 to t3 when the fixing member 9 is moved fromthe first position Ia to the third position Ic, as shown in FIG. 6. Inother words, an excessively heated state in which the SMA wire 14 iscontracted to such a degree that the amount of deformation is equal toor larger than εc is not reached. It can, therefore, be understood thatwhen energization of the SMA wire 14 is stopped, the amount ofdeformation is instantly reduced as indicated by the curve (a) in FIG.6, that is, the SMA wire 14 extends instantly, in comparison with a casewhere the SMA wire 14 is contracted until an amount of deformation of εcor more is reached.

When energization of the SMA wire 14 is stopped at the third position Icshown in FIG. 5, the fixing member 9 is moved toward the distal end sidein the moving direction I by the pressing spring 16 until it is attachedto the magnet 8 at the second position Ib by magnetic force. At thistime, the SMA wire 14 extends so that the amount of deformation of theSMA wire 14 changes from εc to εb as indicated by a curve (b) in FIG. 6.

The magnet 8 is further moved toward the distal end side from the secondposition Ib shown in FIG. 4 by the pressing spring 16 until it isbrought into abutment on the stopper member 35 at the first position Ia.At this time, the moving lens frame 6 and the moving lens 7 are alsomoved in the moving direction I from the second position Ib to the firstposition Ia. Also, the SMA wire 14 extends so that the amount ofdeformation of the SMA wire 14 changes from εb to εa, as indicated bythe curve (b) in FIG. 6.

The non-coincidence between the curves (a) and (b) with respect to thecontraction and the extension of the SMA wire 14 as indicated by thecurve (a) and the curve (b) in FIG. 6, i.e., the difference between theamounts of deformation per unit temperature between the contraction andthe extraction is due to a known hysteretic phenomenon.

It has been described that, in the actuator 20 in the presentembodiment, the magnet 8, the SMA wire 4, the fixing member 9, thepressing spring 16, the stopper portion 31 and the stopper member 35 aredisposed by being arranged in a straight line along the moving directionI, and the moving lens 7 and the moving lens frame 6 that are moved inthe moving direction I in the enclosed space 33 by the magnetic force ofthe magnet 8 are positioned at the first position Ia when the magnet 8is in abutment on the stopper member 35, and are positioned at thesecond position Ib by the magnetic force of the magnet 8 when the magnet8 is maintained in abutment on the stopper portion 31 by contraction ofthe SMA wire 14. It has also been described that when the SMA wire 14 iscontracted from the second position Ib, the fixing member 9 is separatedfrom the magnet 8.

According to this arrangement, in which the magnet 8, the SMA wire 4,the fixing member 9, the pressing spring 16, the stopper portion 31 andthe stopper member 35 are disposed by being arranged in a straight linealong the moving direction I, the actuator 20 is increased in length inthe moving direction I but can be reduced in size in comparison with theone in the conventional arrangement because it is not increased in sizein a diametric direction.

Also, when the SMA wire 14 is contracted from the second position Ib,the fixing member 9 is separated from the magnet 8 while the magnet 8 isin abutment on the stopper portion 31. In this state, the magnet 8 isnot pulled rearward in the moving direction I by the SMA wire 14 withthe fixing member 9. In this way, application of an uncontrollable largeforce to the SMA wire 14 is prevented. As a result, the durability ofthe SMA wire 14 can be improved.

It has also been described that in the present embodiment the SMA wire14 is contracted in the temperature range from t1 to t3 in which anyexcessively heated state is not reached, as described above.

Accordingly, when energization of the SMA wire 14 is stopped toestablish a non-energized state after supplying a current to the SMAwire 14 and thereby contracting the SMA wire 14, the SMA wire 14 extendsat a constant deformation rate. Therefore, the SMA wire 14 can be causedto extend with an increased response speed. As a result, the responsespeed of the actuator 20 is improved.

It has also been described that in the present embodiment the movinglens 7 and the moving lens frame 6 are movable in the moving direction Iin the enclosed space 33 in the second lens frame 32 by the magneticforce of the magnet 8.

Accordingly, permeation of a fluid into the second lens frame 32 isprevented and the gastightness is improved.

Thus, an actuator can be provided which has a configuration in which amoving lens frame and a moving lens are moved by using an SMA wire andthe positions of the moving lens frame and the moving lens are definedby using a stopper portion, and which is capable of preventing areduction in response speed and a reduction in durability and realizinga reduction in size in a diametric direction of the moving lens frameand the moving lens.

A modified example will be described below.

It has been described that, in the present embodiment, the SMA wire 14is contracted so that the magnet 8 abuts on the stopper portion 31 whenthe moving lens frame 6 and the moving lens 7 are moved from the firstposition Ia to the second position Ib, and the fixing member 9 isthereafter separated from the magnet 8.

However, the present invention is not limited thereto. Contraction ofthe SMA wire 14 may be controlled by determining a target current value.This target current value is determined by applying a minute voltagewhen supply of the current to the SMA wire 14 is paused and by detectingthe resistance value with a bridge circuit not shown in the figure.

That is, the amount of energization of the SMA wire 14 may be controlledso that the SMA wire 14 is contracted from the extended state at thefirst position Ia in the non-energized state to the contracted state atthe second position Ib in the energized state.

Further, the abutment between the magnet 8 and the stopper portion 31 atthe second position Ib (the state of abutment) may be detected, forexample, with a sensor such as a short detection circuit provided on thestopper portion 31 and control may be performed on the basis of thedetected state so that a predetermined current is supplied to the SMAwire 14. Detection of abutment between the magnet 8 and the stopperportion 31 may be performed by detecting a change in the value ofresistance against the current for energization of the SMA wire 14.

If the above-described modified example is used, prevention ofapplication of a load to the SMA wire 14 can be achieved withoutseparating the magnet 8 and the fixing member 9 by contacting the SMAwire 14 from the second position Ib, because supply of the current tothe SMA wire 14 is stopped after binging the magnet 8 into abutment onthe stopper portion 31.

Another modified example will be described with reference to FIG. 12.FIG. 12 is a partial sectional view of a distal end portion of anendoscope having an actuator representing a modified example of thepresent embodiment in which a stopper member is provided on the stopperportion shown in FIG. 1.

As shown in FIG. 12, a stopper member 34 made of a magnetic material maybe provided on the stopper portion 31 provided in the second lens frame32. In the case where the stopper member 34 made of a magnetic materialis provided, the magnet 8 and the stopper member 34 attach to each otherby the magnetic force of the magnet 8 when the magnet 8 is moving to Iband, therefore, the magnet 8 remains at the position Ib more reliabilityin comparison with the above-described first embodiment.

Second Embodiment

A second embodiment of the present invention will be described.

FIG. 7 is a partial sectional view of a distal end portion of anendoscope having an actuator representing the present embodiment; FIG. 8is a partial sectional view of the distal end portion of the endoscope,showing a state where a magnet shown in FIG. 7 is brought into abutmenton a stopper portion of a second lens frame; and FIG. 9 is a partialsectional view of the distal end portion of the endoscope, showing astate where the magnet shown in FIG. 7 is in abutment on the stopperportion of the second lens frame, and where a fixing member is movedapart from the magnet.

The configuration of the actuator in the second embodiment differs fromthat of the above-described actuator in the first embodiment shown inFIGS. 1 to 6 in that a magnet directly attaches to a moving lens frameby magnetic force. Description will be made only of this point ofdifference. The same components in the configuration as those in thefirst embodiment are indicated by the same reference numerals, and thedescription thereof will not be repeated.

In the present embodiment, as shown in FIG. 7, a moving lens 47 is heldby a moving lens frame 46 which is a moving portion constituted of amagnetic material, and the moving lens frame 46 is provided so as to bemovable in the moving direction I in the second lens frame 32.

A cut 49 is formed in the second lens frame 32 along the movingdirection I at the lower side of the second lens frame 32 as viewed inFIG. 7, and a connecting rod magnet 48 in the actuator 20 is directlyattached to the moving lens frame 46 through the cut 49 by magneticforce. In other respects, the configuration is the same as that of theabove-described first embodiment.

The operation of the present embodiment thus configured will next bedescribed.

First, when the moving lens 7 is moved to a first position IIa which isa set position corresponding to 1×1 magnification, the SMA wire 14 ofthe actuator 20 is set in a non-energized state. As a result, the SMAwire 14 extends toward the distal end side in the moving direction I,and the fixing member 9 is pressed by the pressing spring 16 toward thedistal end side in the moving direction I to press the connecting rodmagnet 48 against the stopper member 35 in a state of being attached tothe connecting rod magnet 48 by magnetic force, as shown in FIG. 7. As aresult, the moving positions of the moving lens frame 46 and the movinglens 47 are fixed at the distal-most end side, i.e., the first positionIIa corresponding to 1×1 magnification in the moving range from IIa toIIb. Also, at this time, the connecting rod magnet 48 and the stopperportion 31 are separate from each other.

Next, when the moving lens 47 is moved to a second position IIbcorresponding to the maximum magnification, that is, the moving lens 47is moved to the rear end side in the moving direction I, a current issupplied from a power supply not shown in the figure to the drive cable26 in the actuator 20.

Thereafter, the current flows through the drive cable 26, the firstswaged portion 25, the SMA wire 14, the second swaged portion 29 and theGND cable 28, and the SMA wire 14 produces heat and contracts.

As a result, the fixing member 9 is moved rearward in the movingdirection I and the connecting rod magnet 48 that has attached to thefixing member 9 by magnetic force is moved rearward in the movingdirection I through the cut 49 while attaching to the fixing member 9.Further, the moving lens frame 46 and the moving lens 47 are also movedrearward in the moving direction I by the magnetic force of theconnecting rod magnet 48 through the cut 49.

The connecting rod magnet 48 is then brought into abutment on thestopper portion 31 of the second lens frame 32, as shown in FIG. 8. Thestopper portion 31 stops the connecting rod magnet 48 from movingrearward in the moving direction I from the second position IIb, whichis a set position at which the connecting rod magnet 48 abuts on thestopper portion 31, even when the SMA wire 14 contracts. That is, themoving lens frame 46 and the moving lens 47 that have been movedrearward in the moving direction I by the magnetic force of theconnecting rod magnet 48 are defined in the rearmost position in themoving range of the moving lens frame 46 and the moving lens 47. Inother words, the moving lens 47 is moved to the second position IIbcorresponding to the maximum magnification to fix the moving position.At this time, the connecting rod magnet 48 and the stopper member 35 areseparate from each other.

When the SMA wire 14 contracts further in the state where the connectingrod magnet 48 is in abutment on the stopper portion 31 at the secondposition IIb, the fixing member 9 is separated from the connecting rodmagnet 48 and moved rearward in the moving direction I to a thirdposition IIc for example, as shown in FIG. 9.

When the fixing member 9 is separated from the connecting rod magnet 48,the connecting rod magnet 48 remains in abutment on the stopper portion31, and the moving lens frame 46 and the moving lens 47 remain at thesecond position IIb.

Also, when the fixing member 9 is separated from the connecting rodmagnet 48, that is, the SMA wire 14 does not pull the connecting rodmagnet 48 by contraction in the state where the connecting rod magnet 48is in abutment on the stopper portion 31, no excessive load is appliedto the SMA wire 14.

When energization of the SMA wire 14 is stopped at the third positionIIc shown in FIG. 9, the fixing member 9 is moved toward the distal endside in the moving direction I by the pressing spring 16 until it isattached to the connecting rod magnet 48 at the second position IIb bymagnetic force. At this time, the SMA wire 14 extends.

The connecting magnet 48 is further moved toward the distal end side inthe moving direction I from the second position IIb shown in FIG. 8 bythe pressing spring 16 until it is brought into abutment on the stoppermember 35 at the first position IIa through the cut 49. At this time,the moving lens frame 46 and the moving lens 47 are also moved in themoving direction I from the second position IIb to the first positionIIa. The SMA wire 14 is further extended. In other respects, theoperation is the same as that in the above-described first embodiment.

It has been described that in the present embodiment the connecting rodmagnet 48 is directly attached to the moving lens frame 46 by magneticforce through the cut 49. Accordingly, the gastightness on the movinglens frame 46 is reduced as a result of the provision of the cut 49 incomparison with the above-described first embodiment. However, when themoving lens frame 46 moves along the moving direction I, no frictionalresistance is produced between the connecting rod magnet 48 and thesecond lens frame 32 and, therefore, the connecting rod magnet 48 can bemoved more smoothly in comparison with the first embodiment. That is, anactuator having improved response speed can be provided. Other effectsare the same as those in the above-described first embodiment.

While an example of attachment between the second lens frame 32 and theconnecting rod magnet 48 by magnetic force in the second embodiment hasbeen described, the second lens frame 32 and the connecting rod magnet48 may be fixed to each other with an adhesive. If the second lens frame32 and the connecting rod magnet 48 are bonded to each other with anadhesive, the magnetic force of the connecting rod magnet 48 does nothave to be strong and so the connecting rod magnet 48 may have reducedmagnetic force since there is no possibility of disengagement of thesecond lens frame 32 and the connecting rod magnet 48.

Third Embodiment

A third embodiment of the present invention will be described.

FIG. 10 is a partial sectional view of a distal end portion of anendoscope having an actuator representing the present embodiment, andFIG. 11 is a partial sectional view of the distal end portion of theendoscope, showing a state where a magnet shown in FIG. 10 is attachedto a rear magnet in a second lens frame.

The configuration of the actuator in the third embodiment differs fromthat of the above-described actuator in the second embodiment describedabove with reference to FIGS. 7 to 9 in that a connecting rod magnet ismoved in the moving direction between first and second positions bymagnetic force. Description will be made only of this point ofdifference. The same components in the configuration as those in thesecond embodiment are indicated by the same reference numerals, and thedescription thereof will not be repeated.

In the present embodiment, as shown in FIG. 10, a cut 49 is formed inthe second lens frame 32 along the moving direction I at the lower sideof the second lens frame 32 as viewed in FIG. 10, and a connecting rodmagnet 58 in the actuator 20 is directly attached to the moving lensframe 46 through the cut 49 by magnetic force.

A front magnet 57 is provided in a portion of the stopper member 35 onwhich the connecting rod magnet 58 abuts at a first position IIIa. Thefront magnet 57 is disposed so that the magnetic pole of the frontmagnet 57 on the connecting rod magnet 58 side and the magnetic pole ofthe connecting rod magnet 58 on the front magnet 57 side differ inpolarity from each other. For example, the north pole of the frontmagnet 57 and the south pole of the connecting rod magnet 58 are opposedto each other, and the south pole of the front magnet 57 and the northpole of the connecting rod magnet 58 are remote from each other.

Further, a rear magnet 56 is provided in a portion of the second lensframe 32 on which the connecting rod magnet 58 abuts at a secondposition IIIb. The rear magnet 56 is disposed so that the magnetic poleof the rear magnet 56 on the connecting rod magnet 58 side and themagnetic pole of the connecting rod magnet 58 on the rear magnet 56 sideare equal in polarity to each other. For example, the north pole of therear magnet 56 and the north pole of the connecting rod magnet 58 areopposed to each other, and the south pole of the rear magnet 56 and thesouth pole of the connecting rod magnet 58 are remote from each other.

The actuator 20 in the present embodiment is configured differently fromthat in the above-described second embodiment in that the pressingspring and the fixing member are not used. That is, the tip of the SMAwire 14 in the insertion direction S is fixed to the connecting rodmagnet 58. In other respects, the configuration is the same as that ofthe above-described second embodiment.

The operation of the present embodiment thus configured will next bedescribed.

First, when the moving lens 7 is moved to the first position IIIa whichis a set position corresponding to 1×1 magnification, the SMA wire 14 ofthe actuator 20 is set in a non-energized state. As a result, the SMAwire 14 extends toward the distal end side in the moving direction I,and the south pole of the connecting rod magnet 58 and the north pole ofthe front magnet 57 are attached to each other by magnetic force, asshown in FIG. 10.

As a result, the moving positions of the moving lens frame 46 and themoving lens 47 are fixed at the distal-most end side in the movingdirection I, i.e., the first position IIIa corresponding to 1×1magnification in the moving range from IIIa to IIIb.

Next, when the moving lens 47 is moved to the second position IIIbcorresponding to the maximum magnification, that is, the moving lens 47is moved to the rear end side in the moving direction I, a current issupplied from a power supply not shown in the figure to the drive cable26 in the actuator 20.

Thereafter, the current flows through the drive cable 26, the firstswaged portion 25, the SMA wire 14, the second swaged portion 29 and theGND cable 28, and the SMA wire 14 produces heat and contracts.

As a result, the connecting rod magnet 58 is moved rearward in themoving direction I by the contraction of the SMA wire 14. Further, themoving lens frame 46 and the moving lens 47 are also moved rearward inthe moving direction I by the magnetic force of the connecting rodmagnet 58.

The connecting rod magnet 58 is then brought into abutment on the rearmagnet 56 in the second lens frame 32, as shown in FIG. 11. At thistime, since each of the magnetic poles of the connecting rod magnet 58and the rear magnet 56 is a north pole, these magnets repel each other.However, the contracting force of the SMA wire 14 is larger than therepelling force, so that the connecting rod magnet 58 is brought intoabutment of the rear magnet 56 in the second lens frame 32.

Because of the existence of the rear magnet 56, the connecting rodmagnet 58 is not moved rearward in the moving direction I from thesecond position IIIb even if the SMA wire 14 is further contracted. Thatis, the rearmost positions of the moving lens frame 46 and the movinglens 47 that have moved backward in the moving direction I by themagnetic force of the connecting rod magnet 58 in the moving range areset. In other words, the moving lens 47 is moved to the second positionIIIb corresponding to the maximum magnification to fix the movingposition.

If in the present embodiment the SMA wire 14 is contracted in the statewhere the connecting rod magnet 58 is in abutment on the rear magnet 56,there is a possibility of a load being applied to the SMA wire 14.However, if energization amount control is performed on the SMA wire 14as described above, application of a load to the SMA wire 14 can beprevented.

When energization of the SMA wire 14 is stopped at the second positionIIIb shown in FIG. 11, the connecting rod magnet 58 is moved toward thedistal end side in the moving direction I by repellency due to equalityin polarity (north pole) between the connecting rod magnet 58 and therear magnet 56 opposed to each other until the connecting rod magnet 58is attached to the front magnet 57 at the first position IIIa. At thistime, the moving lens frame 46 and the moving lens 47 are also moved inthe moving direction I from the second position IIIb to the firstposition IIIa. The SMA wire also extends. In other respects, theoperation is the same as that in the above-described second embodiment.

It has been described that in the present embodiment the front magnet 57having a magnetic pole differing in polarity from a magnetic pole of theconnecting rod magnet 58 facing the magnetic pole of the front magnet 57is disposed in the stopper member 35 on which the connecting rod magnet58 abuts at the first position IIIa, and the rear magnet 56 having amagnetic pole equal in polarity to a magnetic pole of the connecting rodmagnet 58 facing the magnetic pole of the rear magnet 56 is disposed inthe second lens frame 32 on which the connecting rod magnet 58 abuts.

According to this arrangement, the front magnet 57 and the rear magnet56 are disposed in place of the pressing spring in the actuator 20 toenable the actuator 20 to be reduced in a diametric direction by anamount corresponding to the thickness of the pressing spring in thediametric direction. Also, since the structure is simplified, theassembly of the actuator 20 is made easier. Other effects are the sameas those in the third embodiment.

In the first to third embodiments, the moving lens frame holding themoving lens has been described by way of example as a moving portionmoved in the moving direction I with an actuator. However, the presentinvention is not limited thereto. Needless to say, any moving portionmoved by using an actuator may suffice if moves rectilinearly.

In the first to third embodiments, the actuator has been described withrespect to use in an endoscope. However, the present invention is notlimited thereto. Needless to say, the actuator may be used in any otherthing.

Fourth Embodiment

A fourth embodiment of the present invention will be described withreference to the drawings. In the present embodiment, an example of animage pickup apparatus incorporated in a rigid electronic endoscope usedin a laparoscopic surgery among endoscopic apparatuses provided as amedical apparatus inserted in a body cavity to observe a living tissue.

An image pickup apparatus according to the fourth embodiment of thepresent invention will be described with reference to FIGS. 13 to 22.

FIGS. 13 to 22 relate to the fourth embodiment of the present invention;FIG. 13 is a diagram showing the configuration of a rigid electronicendoscope; FIG. 14 is a sectional view of an image pickup apparatusdisposed in a distal end portion of the rigid electronic endoscope; FIG.15 is a sectional view taken along line XV-XV in FIG. 14; FIG. 16 is anexploded perspective view of a diaphragm unit; FIG. 17 is a front viewof the diaphragm unit; FIG. 18 is a sectional view taken along lineXVIII-XVIII in FIG. 17; FIG. 19 is a sectional view showing a state inwhich a moving lens unit is positioned rearward; FIG. 20 is a sectionalview taken along line XX-XX in FIG. 19; FIG. 21 is a sectional viewshowing a state in which the moving lens unit is positioned forward; andFIG. 22 is a sectional view taken along line XXII-XXII in FIG. 21.

As shown in FIG. 1, a rigid electronic endoscope 60 (hereinafterreferred to simply as “endoscope”) 1 is configured mainly of aninsertion portion 61, an operation portion 62 provided continuously witha proximal end of the insertion portion 61, a universal cord 63extending from the operation portion 62, a scope connector 64 providedon a proximal end of the universal cord 63, and an electric connector 65provided on an end portion of a cable extending from a side portion ofthe scope connector 64.

The insertion portion 61 of the endoscope 60 is configured of, in orderfrom a distal end, a distal end portion 66, a bending portion 67provided continuously with the distal end portion 66, a rigid tubeportion 68 provided between the bending portion 67 and an operationportion 62. The rigid tube portion 68 in the present embodiment isformed of a nonflexible rigid tube formed from stainless steel or thelike. An image pickup apparatus having an image pickup optical systemdescribed below is incorporated in the distal end portion 66.

The operation portion 62 of the endoscope 60 in the present embodimentis provided with two bending operation levers 69 and 70 operated byturning operations to perform an operation to bend the bending portion67, and switches 71 for performing various operations. These bendingoperation levers 69 and 70 are operated in a turning manner to bend thebending portion 67 of the insertion portion 61 in four or twodirections. The plurality of switches 71 provided on the operationportion 62 are operated when predetermined endoscopic functions, e.g.,operations on the image pickup apparatus disposed in the distal endportion 66 are executed.

The endoscope 60 in the present embodiment has the scope connector 64connected to a light source unit incorporating an illumination meanssuch as a halogen lamp, and has the electric connector 65 connected to avideo processor, although these connections are not shown in the figure.

Illumination light from the light source unit is transmitted through alight guide bundle passed from the universal cord 63 to the distal endportion 66 to be radiated from the distal end portion 66 to a subject.The video processor is connected to a monitor and outputs an endoscopicimage picked up with the endoscope 60 to the monitor to display theimage.

The image pickup apparatus in the present embodiment, disposed in thedistal end portion 66 of the endoscope 60, will be described in moredetail with reference to FIGS. 14 and 15.

As shown in FIG. 14, the image pickup apparatus 72 in the presentembodiment is configured mainly of a lens unit 73, an image pickupelement unit 83 fitted to the lens unit 73 at the rear of the same, anda movable lens drive mechanism 89 disposed along portions of outerperipheries of the lens unit 73 and the image pickup element unit 83.

The lens unit 73 is configured of a front lens group 74 constituting afront objective optical system including an observation lens disposed ata distal end surface of the distal end portion 66, a fixed front lensgroup frame 76 which is a fixed lens frame holding the front lens group74 and formed of a nonmagnetic material, a fixed rear lens group frame77 which is a fixed lens frame provided fittingly and continuously witha rear end portion of the fixed front lens group frame 76, holding arear lens group 79 constituting a rear objective optical system, andformed of a nonmagnetic material in substantially cylindrical form, anda movable lens unit 102 disposed in the fixed rear lens group frame 77so as to be able to move forward and rearward, and having a diaphragmunit 80 fitted and fixed in a distal end portion thereof.

The fixed rear lens group frame 77 has a permanent magnet (hereinafterreferred to simply as “magnet”) 81 fitted in an outer peripheral portionon the distal end side. A permanent magnet is used as the magnet 81 inthe present embodiment. The magnet 81 is disposed at the upper side ofthe fixed rear lens group frame 77 as viewed toward the paper surface inFIG. 14.

The movable lens unit 102 is configured of a movable lens frame 103formed of a nonmagnetic material, a magnetic member 104 fitted to aproximal end of the movable lens frame 103 and formed of a magneticmaterial in ring form, and a movable lens 105 held in the movable lensframe 103. The movable lens unit 102 is guided so as to be able to movestraight forward or rearward along a shooting optical axis O in themovable lens frame 103.

The image pickup element unit 83 is configured mainly of a holding frame84 holding an optical component 85 such as a cover glass, a solid-stateimage pickup element 86 which is an image sensor such as a CCD or a CMOSbonded to the optical component 85 so that its light receiving portionis surface-joined thereto, and a flexible printed circuit (FPC) 75 inwhich electronic component parts electrically connected to thesolid-state image pickup element 86 are mounted and to which a pluralityof communication lines 87 are electrically connected by soldering.

A distal end portion of the holding frame 84 is fitted and fixed in thefixed rear lens group frame 77 of the lens unit 73, and aheat-shrinkable tube 88 for covering and protecting the solid-stateimage pickup element 86 and other components is provided on a proximalend outer peripheral portion of the holding frame 84. The space in theheat-shrinkable tube 88 is filled with a protective adhesive so as tocover the solid-state image pickup element 86, the FPC 75 and thecommunication lines 87.

The movable lens drive mechanism 89 is configured of a frame 90 in whicha guide groove 91 which is a recessed groove parallel to the shootingoptical axis O is formed and having a concave shape is formed, a magnethold base 92 guided and moved rectilinearly in the guide groove 91 andformed of a nonmagnetic material, a movable magnet 93 which is apermanent magnet fitted in an upper portion of the magnet hold base 92,a spring 94 which urges the magnet hold base 92 forward, a shape memoryalloy (SMA) wire 95 joined to a proximal end portion of the magnet holdbase 92, a pipe 98 made of a metal, e.g., stainless steel and fitted toa proximal end of the frame 90, an insulating tube 99, through which theSMA wire 95 in inserted, such as a PEEK tube having an insulatingproperty and inserted in the pipe 98, a swaged electrode fitting 100which is provided on a proximal end of the insulating tube 99, and towhich the SMA wire 95 is joined, a power supply cable 101 electricallyconnected to the waged electrode fitting 100, and an insulating sheath106 which covers a distal end portion of the insulating tube 99 and theswaged electrode fitting 100 as well as the power supply cable 101. TheSMA wire 95 is connected to a proximal end portion of the magnet holdbase 92 and thereafter bent back to be extended rearward as a ground(GND) wire 96 described below.

As shown in FIG. 15, the frame 90 is substantially U-shaped in sectionand has its upper end portions fitted to the fixed rear lens group frame77 of the lens unit 73. In this fitted state, a space surrounded by anoutside shape surface of the fixed rear lens group frame 77 and aninside shape surface of the frame 90 is formed. In this space, themagnet hold base 92 is guided by the guide groove 91 to move straightforward or rearward in a direction parallel to the shooting optical axisO together with the movable magnet 93.

For this forward/rearward movement of the magnet hold base 92, electricpower is supplied from the power supply cable 101 to the SMA wire 95connected to the rear end portion of the magnet hold base 92 via theswaged electrode fitting 100 to cause the SMA wire 95 itself to produceheat, contract and pull the magnet hold base 92 rearward against theforward urging force of the spring 94. The magnet hold base 92 is thusenabled to move rearward.

When the supply of electric power to the SMA wire 95 is stopped, the SMAwire 95 is returned to ordinary temperature to enable the magnet holdbase 92 to move forward by receiving the forward urging force of thespring 94. After the magnet hold base 92 has been enabled to moveforward, the distal end surface thereof is brought into abutment on anabutment member 82 fitted in a distal end of the frame 90 to limit theforward movability.

The SMA wire 95 is turned back at the magnet hold base 92 andelectrically connected to the ground (GND) wire 96 (see FIG. 15)extending rearward and covered with an insulating tube 97.

The magnet hold base 92 is thus moved forward or rearward in thedirection parallel to the shooting optical axis O together with themovable magnet 93. When the magnet hold base 92 moves in this way, themagnetic member 104 provided on the proximal end portion of the movablelens frame 103 is attracted by receiving magnetic force from the movablemagnet 93 from the outside of the fixed rear lens group frame 77 to moveforward or rearward in the direction parallel to the shooting opticalaxis O in the fixed rear lens group frame 77 together with the movablelens frame 103 by being interlocked with the forward/rearward movementof the movable magnet 93.

In other words, the movable lens unit 102 moves forward or rearward inthe fixed rear lens group frame 77 by receiving magnetic action from themovable magnet 93 through the magnetic member 104 on the movable lensframe 103 holding the movable lens 105.

The distance through which the movable lens unit 102 moves forward orrearward is according to the focal distance corresponding to apredetermined zoom/telephoto state of the image pickup apparatus 72variable with the movability of the movable lens 105 along the shootingoptical axis O.

With respect to the rearward movability of the movable lens unit 102, alimiting projection 78 which projects inwardly in a diametric directionand which limits the movable position by abutting on a proximal endsurface of the magnetic member 104 provided on the proximal end of themovable lens frame 103 is formed on an inner peripheral surface of thefixed rear lens group frame 77. With respect to the forward movabilityof the movable lens unit 102, a distal end surface of the movable lensframe 103 is brought into abutment on a proximal end surface of thefixed front lens group frame 76 to limit the movement.

That is, the movable range of the movable lens unit 102 along theshooting optical axis is defined between the position at which themovable lens frame 103 abuts on the fixed front lens group frame 76 andthe position at which the magnetic member 104 abuts on the limitingprojection 78 of the fixed rear lens group frame 77.

Further, the movable lens unit 102 moves forward or rearward in anenclosed space in the fixed rear lens group frame 77 closed in a sealingmanner at the distal end with the front lens group 74 and the fixedfront lens group frame 76 and closed with the rear lens group 79. Thatis, the image pickup apparatus 72 in the present embodiment isconfigured to move forward or rearward the movable lens unit 102 in theenclosed space in the fixed rear lens group frame 77 by the movable lensdrive mechanism 89, thus being configured to have good moistureresistance.

The image pickup apparatus 72 in the present embodiment is alsoconfigured to enable selection between two states: a wide-angle state inwhich the movable lens unit 102 is positioned forward, and a telephotostate in which the movable lens unit 102 is positioned rearward, and theopening diameter φ of the diaphragm unit 80 optimizing the quality oflight is variable according to the focal distances corresponding tothese states.

The diaphragm unit 80 of the present embodiment in which the openingdiameter φ is variable will be described in detail with reference toFIGS. 16 to 18.

As shown in FIG. 16, the diaphragm unit 80 is configured of a fixeddiaphragm plate 107 having a diaphragm hole 108 at its center and formedof a nonmagnetic material in disk form, a diaphragm frame 109 formed ofa nonmagnetic member in annular form, two retaining plates 110 formed ofa nonmagnetic member in substantially semicircular form constituting adiaphragm blade retainer, a movable diaphragm blade 112 having adiaphragm hole 113 in its upper portion, having a cut 123 in its lowerportion and formed of a magnetic material, and a spring 116 which is anurging member having one end portion fixed to an upper end portion ofthe movable diaphragm blade 112.

In the fixed diaphragm plate 107, an opening diameter φA of thediaphragm hole 108 (see FIG. 18) for adjusting the amount of shootinglight in the optical system of the present embodiment by allowing onlypart of the shooting light to pass through the formed diaphragm hole 108to satisfy a predetermined optical performance requirement is set. PTFEsurface working or the like for reducing sliding frictional resistanceto the movable diaphragm blade 112 is performed on the fixed diaphragmplate 107.

The outer peripheral surface of the diaphragm member 109 substantiallycoincides with the outside shape of the fixed diaphragm plate 107 andhas a predetermined thickness larger than those of the movable diaphragmblade 112 and the retaining plates 110.

The two retaining plates 110 are disposed by being opposed to each otherand have guide grooves 111 formed in edge portions on one side thereoffacing each other when the retaining plates 110 are opposed to eachother, as also described below. The guide grooves 111 guide the movablediaphragm blade 112 for vertical rectilinear movement bysurface-contacting and slidably retaining opposite end portions of themovable diaphragm blade 112, while the movable diaphragm blade 112 is incontact with the fixed diaphragm plate 107. PTFE surface working or thelike for reducing sliding frictional resistance to the movable diaphragmblade 112 is also performed on surfaces in the guide grooves 111.

PTFE surface working or the like for reducing sliding frictionalresistance is performed on the movable diaphragm blade 112. In thediaphragm hole 113 formed in the movable diaphragm blade 112, an openingdiameter φB (see FIG. 18) for adjusting the amount of shooting light inthe optical system of the present embodiment by allowing only part ofthe shooting light to pass to satisfy a predetermined opticalperformance requirement, smaller than the opening diameter φA of thediaphragm hole 108, is set.

In the movable diaphragm blade 112, the cut 123 extending on the side ofa lower portion opposite from the upper portion on which the spring 116is provided and having an upper portion cut into a circular-arc shape isformed. The cut 123 is formed so as to be larger than the diaphragm hole108 of the fixed diaphragm plate 107.

The diaphragm frame 109 is fixed to a circumferential portion of onesurface of the fixed diaphragm plate 107. The movable diaphragm blade112 is disposed so as to surface-contact with the one surface of thefixed diaphragm plate 107 on which the diaphragm frame 109 is fixed.

Another end portion of the spring 116 opposite from the one end portionfixed to the movable diaphragm blade 112 is fixed to an inner surface ofthe diaphragm frame 109 by bonding with an adhesive or the like. Themovable diaphragm blade 112 has its two side portions brought intoengagement with the guide grooves 111 of the fixed diaphragm plate 107by the two retaining plates 110 and is vertically slidably interposedbetween the fixed diaphragm plate 107 and the two retaining plates 110while being pressed against the fixed diaphragm plate 107. The tworetaining plates 110 are fixed to the diaphragm frame 109 in a state ofbeing spaced apart from each other by such a distance as not to closethe diaphragm holes 108 and 74 a.

The diaphragm unit 80 of the present embodiment thus assembled is fittedand fixed in a distal end portion of the movable lens frame 103 of themovable lens unit 102, as shown in FIG. 2, while positioning the movablediaphragm blade 112 on the front side, as shown in FIGS. 17 and 18.

Detailed description will be made below, with reference to FIGS. 19 to22, of an action to vertically move the movable diagram blade 112 in thediaphragm unit 80 interlocked with the forward/rearward movement of themovable lens unit 102 along the shooting optical axis O in the imagepickup apparatus 72 of the present embodiment thus configured.

To establish a telephoto state by rearward positioning, as shown inFIGS. 19 and 20, in the image pickup apparatus 72 in the presentembodiment, a current is applied to the SMA wire 95 to cause the SMAwire 95 to contract, as described above. The magnet hold base 92 onwhich the movable magnet 93 is provided is thereby pulled rearwardagainst the forward urging force of the spring 94.

Then, the magnetic member 104 of the movable lens unit 102 is attractedto the movable magnet 93 by magnetic action and is moved rearward in thefixed rear lens group frame 77 by being interlocked with the movablemagnet 93, and the proximal end surface of the magnetic member 104 isbrought into abutment on the limiting projection 78 of the fixed rearlens group frame 77 to limit the rearward movement. The movable lensunit 102 is thereby stopped at the telephoto position corresponding tothe predetermined set focal distance.

At this time, a downward urging force of the movable magnet 93 side isapplied to the movable diaphragm blade 112 of the diaphragm unit 80 bythe spring 116 on the upper portion side. As a result the lower endportion of the movable diaphragm blade 112 is brought into abutment onthe diaphragm frame 109. In this state, the diaphragm hole 113 of themovable diaphragm blade 112 is aligned with a center of the diaphragmhole 108 of the fixed diaphragm plate 107, and the movable diaphragmblade 112 is superposed so as to cover the periphery of the diaphragmhole 108. That is, at this time, the diaphragm unit 80 has the stopvalue for adjusting the amount of shooting light according to theopening diameter φB of the diaphragm hole 113 of the movable diaphragmblade 112.

To establish a wide-angle state by forward positioning, in the presentembodiment, as shown in FIGS. 21 and 22, in the image pickup apparatus72 shown in FIG. 14, application of the current to the SMA wire 95 isstopped to restore the length of the SMA wire 95 at ordinarytemperature. The magnet hold base 92 on which the movable magnet 93 isprovided is moved by being pushed forward by the urging force of thespring 94.

At this time, by the magnetic member 104 receiving the magnetic actionfrom the movable magnet 93, the movable lens unit 102 is moved forwardin the fixed rear lens group frame 77 in a state of being interlockedwith the movement of the movable magnet 93. The distal end surface ofthe movable lens frame 103 is then brought into abutment on the proximalend surface of the fixed front lens group frame 76 to limit the forwardmovement of the movable lens unit 102. The movable lens unit 102 isthereby stopped at the zooming position corresponding to thepredetermined set focal distance.

At this time, the movable diaphragm blade 112 of the diaphragm unit 80is moved upward by being attracted to the magnet 81 provided in theupper portion of the fixed rear lens group frame 77 against the downwardurging force of the spring 116 on the upper portion side, as shown inFIG. 22. That is, when the diaphragm unit 80 is moved forward togetherwith the movable lens unit 102, it is moved to a position close to themagnet 81 in the fixed rear lens group frame 77. Therefore the movablediaphragm blade 112 formed of a magnetic material receives the magneticaction of the magnet 81 to be attracted while being guided by the guidegrooves 111 of the retaining plates 110 so as to be move rectilinearly.

In this state, the diaphragm hole 113 of the movable diaphragm blade 112is moved to a position above the diaphragm hole 108 of the fixeddiaphragm plate 107, and the diaphragm hole 108 is exposed through thecut 123. That is, at this time, the diaphragm unit 80 has the stop valuefor adjusting the amount of shooting light according to the openingdiameter φA of the diaphragm hole 108 of the fixed diaphragm plate 107.

Thus, in the image pickup apparatus 72 of the present embodiment, themovable diaphragm blade 112 of the diaphragm unit 80 is moved verticallyby being guided in rectilinear movement by the guide grooves 111 of theretaining plates 110 according to the forward/rearward movement of themovable lens unit 102 along the shooting optical axis O according to thetwo telephoto and wide-angle states.

That is, when the diaphragm unit 80 is moved forward together with themovable lens unit 102, the movable diaphragm blade 112 formed of amagnetic material is brought close to the magnet 81 and thereforereceives magnetic force from the magnet 81 to be attracted to the magnet81 by the force larger than the urging force of the spring 116.Meanwhile, when the diaphragm unit 80 is moved rearward together withthe movable lens unit 102, the movable diaphragm blade 112 is moved awayfrom the magnet 81 and the magnetic force from the magnet 81 is reduced.As a result, the urging force of the spring 116 prevails over themagnetic force and the movable diaphragm blade 112 moves downward.

The magnet 81 is disposed at a position shifted further forward in thefront-rear-direction along the shooting optical axis, i.e., in thefront-rear direction along the major axis of the image pickup apparatus72, relative to the position to which the movable magnet 93 is movedforward to reach the wide-angle position, and opposite from the movablemagnet 93 with respect the shooting optical axis O. In the presentembodiment, the positions in which the magnets 81 and 93 are disposed,the magnetic forces of the magnets 81 and 93 acting on the movablediaphragm blade 112 and the urging force of the spring 116 are set sothat even when the movable diaphragm blade 112 formed of a magneticmaterial receives the urging force of the spring 116 and magnetic forcefrom the movable magnet 93 at the position reached by forward movementto establish the wide-angle state, the movable diaphragm blade 112 canbe sufficiently moved upward by the magnetic force of the magnet 81.Also, the position in which the magnet 81 is disposed, the magneticforce of the magnet 81 acting on the movable diaphragm blade 112 and theurging force of the spring 116 are set so that even when the movablediaphragm blade 112 formed of a magnetic material receives magneticforce from the movable magnet 81 at the position reached by rearwardmovement to establish the telephoto state, the movable diaphragm blade112 can be sufficiently moved downward by the urging force of the spring116.

As described above, the image pickup apparatus 72 provided with thezooming function according to the present embodiment is arranged to movethe movable lens unit 102 forward and rearward along the shootingoptical axis O in the enclosed space by the magnetic action of themovable lens drive mechanism 89, thereby has a structure with goodmoisture resistance, and can also have a simple structure in which thediaphragm is opened and closed by the magnetic action of the diaphragmunit 80 capable of changing the amount of shooting light according to atelephoto state or a wide-angle state. In particular, the image pickupapparatus 72 of the present embodiment is smaller in size but hasadvantageously improved assembly facility because the structure forchanging the diaphragm by the diaphragm unit 80 is simple.

Needless to say, the above-described configuration may be provided inthe image pickup apparatuses described above in the descriptions of thefirst to third embodiments.

Fifth Embodiment

A fifth embodiment of the present invention will be described below withreference to FIGS. 23 to 27.

FIGS. 23 to 27 relate to the fifth embodiment of the present invention;FIG. 23 is a partial sectional view showing a configuration for an imagepickup apparatus; FIG. 24 is a sectional view showing a state in which amovable lens unit is positioned rearward; FIG. 25 is a sectional viewtaken along line XXV-XXV in FIG. 24; FIG. 26 is a sectional view showinga state in which the movable lens unit is positioned forward; and FIG.27 is a sectional view taken along line XXVII-XXVII in FIG. 26. In thefollowing description, the same components in the configuration as thosein the above-described fourth embodiment are indicated by the samereference numerals, and the detailed description thereof will not berepeated.

In the image pickup apparatus 72 of the present embodiment, thediaphragm unit 80 is fitted and fixed to a proximal end portion of thefixed front lens group frame 76. Also, a magnet 117 is fittinglydisposed in an upper portion in a distal end portion of the movable lensframe 103 of the movable lens unit 102. Further, in the fixed rear lensgroup frame 77, a magnet 118 is fittingly disposed at a distal-end lowerouter peripheral position immediately below the diaphragm unit 80.

That is, the image pickup apparatus 72 of the present embodiment isconfigured by disposing on the fixed front lens group frame 76 thediaphragm unit 80 fixed in the movable lens unit 102 in the fourthembodiment.

Also in the thus-configured image pickup apparatus 72 in the presentembodiment, when a telephoto state is established by rearwardpositioning, as shown in FIG. 24, the movable diaphragm blade 112 of thediaphragm unit 80 receives the magnetic force of the magnet 118 providedimmediately below the diaphragm unit 80 to be attracted to a lowerposition on the magnet 118 side, thereby bringing the lower end portioninto abutment on the diaphragm frame 109 as shown in FIG. 25. In thisstate, the diaphragm hole 113 of the movable diaphragm blade 112 isaligned with a center of the diaphragm hole 108 of the fixed diaphragmplate 107, and the movable diaphragm blade 112 is superposed so as tocover the periphery of the diaphragm hole 108. That is, at this time,the diaphragm unit 80 has the stop value for adjusting the amount ofshooting light according to the opening diameter φB of the diaphragmhole 113 of the movable diaphragm blade 112.

Meanwhile, also in the image pickup apparatus 72 in the presentembodiment, when a wide-angle state is established by forwardpositioning, as shown in FIG. 26, the movable diaphragm blade 112 of thediaphragm unit 80 receives the magnetic force of the magnet 117 providedin a distal end upper portion of the movable lens frame 103 and isattracted by this force to move upward against a downward attractionforce based on the magnetic force of the magnet 118 existing immediatelybelow, as shown in FIG. 27. That is, when the movable lens unit 102 ismoved forward, the magnet 117 in the movable lens frame 103 is moved toa position close to an upper portion of the diaphragm unit 80 and,therefore, the movable diaphragm blade 112 formed of a magnetic materialreceives the magnetic action of the magnet 117 to be attracted upwardwhile being guided by the guide grooves 111 of the retaining plates 110so as to be move rectilinearly.

In this state, the diaphragm hole 113 of the movable diaphragm blade 112is moved to a position above the diaphragm hole 108 of the fixeddiaphragm plate 107, and the diaphragm hole 108 is exposed through thecut 123. That is, at this time, the diaphragm unit 80 has the stop valuefor adjusting the amount of shooting light according to the openingdiameter φA of the diaphragm hole 108 of the fixed diaphragm plate 107.

That is, when the movable lens unit 102 is moved forward, the magnet 117is moved closer to the movable diaphragm blade 112 formed of a magneticmaterial and the movable diaphragm blade 112 receives the magnetic forceof the magnet 117 and moves upward by being attracted by the magneticforce larger than the magnetic force of the magnet 118. Meanwhile, whenthe movable lens unit 102 is moved rearward, the magnet 117 is movedaway from the movable diaphragm blade 112 and the magnetic force fromthe magnet 117 is reduced. As a result, the magnetic force of the magnet118 prevails over the magnetic force from the magnet 117 and the movablediaphragm blade 112 moves downward.

The magnetic force of the magnet 117 of the movable lens unit 102 is setto a value higher than that of the magnet 118 disposed in the fixed rearlens group frame 77 opposite from the magnet 117 with respect to theoptical axis O when the movable lens unit 102 is moved forward, whichvalue is high enough to attract the movable diaphragm blade 112 againstthe magnetic force of the magnet 118.

The diaphragm unit 80 of the present embodiment is configured to advanceand retract the movable diaphragm blade 112 in a direction perpendicularto the shooting optical axis O by means of the two magnets 117 and 118and, therefore, as shown in FIGS. 25 and 27, does not require the spring116 provided in the fourth embodiment.

The image pickup apparatus 72 of the present embodiment can have thesame advantages as those of the apparatus of the first embodiment and isfree from the need for the provision of the spring 116 in the diaphragmunit 80. Therefore, only a relationship of magnetic force may be setbetween the two magnets 117 and 118 and the configuration is simplified.

The diaphragm unit 80 described in each of the above-describedembodiments is only an example. Configurations such as shown in FIGS. 28to 31 may alternatively be adopted. FIG. 28 is a front view of aconfiguration of a diaphragm unit according to a first modified example;FIG. 29 is a sectional view taken along line XXIX-XXIX in FIG. 28; FIG.30 is a front view of a configuration of a diaphragm blade according toa second modified example; and FIG. 31 is a front view of aconfiguration of a diaphragm blade according to a third modifiedexample.

For example, as shown in FIGS. 28 and 29, the configuration of a movablediagram blade 114 in the diaphragm unit 80 differs from that in eachembodiment. More specifically, the movable diagram blade 114 is formedof a magnetic material, and an extended end portion of an arm portionextending from a circular outer peripheral portion in which thediaphragm hole 113 is formed is turnably disposed on the fixed diaphragmplate 107 by means of a blade shaft 119.

A spring attachment member 122 is disposed on the arm portion of themovable diaphragm blade 114, and one end of a spring 121 is connected tothe spring attachment member 122. The spring 121 urges the movablediaphragm blade 114 in such a manner that the movable diaphragm blade114 is pulled downward. The other end of the spring 121 is fixed in aninner surface of the diaphragm frame 109.

On the fixed diaphragm plate 107, a blade stop member 120 to be broughtinto abutment on the movable diaphragm blade 114 urged by the spring 121to limit the position of the movable diaphragm blade 114 at a positionat which the diaphragm hole 113 of the movable diaphragm blade 114 issuperposed on the diaphragm hole 108 is provided.

Also in the thus-configured diaphragm unit 80, the movable diaphragmblade 114 receives magnetic force from a magnet which is brought closerthereto with the advancing/retracting movement of the movable lens unit102 or the forward movement in the telephoto state of the image pickupapparatus 72, as in each of the embodiments described above, and isthereby given a force for upward attraction to be turned upward on theblade shaft 119 against the urging fore of the tensile force of thespring 121.

Meanwhile, with the rearward movement of the movable lens unit 102 inthe wide-angle state of the image pickup apparatus 72, the magneticforce from the magnet is reduced and the movable diaphragm blade 114 isturned by being pulled downward by the spring 121 to be brought intoabutment on the blade stop member 120 and stopped at the position atwhich the diaphragm hole 113 is superposed on the diaphragm hole 108.

Thus, the diaphragm unit 80 constitutes a mechanism to change theopening diameter φ of the diaphragm. Also with the thus-configureddiaphragm unit 80, the same advantages and effects as those in theabove-described embodiments can also be obtained.

It is preferable to provide the movable diaphragm blade 112 with a slit115 connecting the diaphragm hole 113 and the cut 123, as shown in FIG.30. The slit 115 is formed at a position at which the shooting opticalpath O passes through the movable diaphragm blade 112 inadvancing/retracting movement.

The slit 115 is provided in the movable diaphragm blade 112 in this wayto avoid an instantaneous break of the shooting optical path O at thetime of advancing/retracting movement of the movable diaphragm blade112, thus preventing instantaneous disappearance of an image taken bythe image pickup apparatus 72 at the time of telephoto/wide-angleswitch. Also, the image pickup apparatus 72 is capable of preventingdisappearance of a taken image even in a case where the movablediaphragm blade 112 stops halfway through the advancement or retractionstroke before correctly advancing or retracting due to some fault.

Further, the cut 123 formed in the movable diaphragm blade 112 may onlyenable the diaphragm hole 108 of the fixed diaphragm plate 107 to becompletely exposed when the movable diaphragm blade 112 is moved upward.Therefore, the cut 123 may be formed into any shape, e.g., a shapehaving a semicircular upper portion and vertically extending lowerportions, as shown in FIG. 31.

In each of the above-described embodiments, a permanent magnet is usedas the magnet for magnetically moving the movable diaphragm blade 112for the purpose of simplifying the configuration. However, the presentinvention is not limited thereto. An electromagnet or the like mayalternatively be used.

Further, while the movable diaphragm blade 112 is formed as a magneticmember, the movable diaphragm blade 112 itself may be a magnet. In sucha case, the polarities of the magnets may be set with respect toattraction and repellency between the magnets according to the movabledirections.

The invention described by referring to the embodiments is not limitedto the embodiments and the modified examples. Various changes andmodifications may be made in the embodiments and modified examples in animplementation stage without departing from the gist of the invention.Further, the above-described embodiments include variations of theinvention in various stages, which can be extracted according tosuitable combinations of the plurality of constituent featuresdisclosed.

For example, if the problems to be solved by the invention can be solvedand the described effects can be obtained even in a case where severalones of all the constituent features described in the embodiments aredeleted, a configuration as a result of deletion of the constituentfeatures can be extracted as the invention.

Having described the preferred embodiments of the invention referring tothe accompanying drawings, it should be understood that the presentinvention is not limited to those precise embodiments and variouschanges and modifications thereof could be made by one skilled in theart without departing from the spirit or scope of the invention asdefined in the appended claims.

1. An actuator comprising: a magnet moved together with a movingportion; a shape memory alloy wire capable of extending and contractingin a direction of movement of the moving portion with execution ornon-execution of energization thereof; a fixing member attached to adistal end of the shape memory alloy wire; a spring which urges thefixing member toward the magnet along the direction of movement; and astopper portion which limits the movement of the magnet along thedirection of movement at a set position.
 2. The actuator according toclaim 1, wherein the fixing member is constituted of a magneticmaterial.
 3. The actuator according to claim 1, wherein the movingportion is constituted of a magnetic material, and the magnet is movedby magnetic force together with the moving portion.
 4. The actuatoraccording to claim 1, wherein a nonmagnetic member is provided along thedirection of movement between the moving portion and the magnet, and themagnet is moved together with the moving portion in non-contact with themoving portion by means of the nonmagnetic member.
 5. The actuatoraccording to claim 2, wherein, in a state where the shape memory alloywire is not energized and where the shape memory alloy wire is extended,the magnet and the fixing member are attached to each other by magneticforce under urging with the spring, while the magnet and the stopperportion are separate from each other in the moving direction.
 6. Theactuator according to claim 2, wherein, in a state where the shapememory alloy wire is energized and where the shape memory alloy wire iscontracted, the magnet is in abutment on the stopper portion at the setposition while the fixing member is attached to the magnet, and thefixing member is separated from the magnet if the shape memory alloywire is further contracted from the set position.
 7. The actuatoraccording to claim 1, wherein the amount of energization of the shapememory alloy wire is controlled so that the shape memory alloy wire iscontracted by a set amount from the expanded state when the shape memoryalloy wire is not energized to the contracted state at the set positionwhen the shape memory alloy wire is energized.
 8. The actuator accordingto claim 1, wherein a state of abutment between the magnet and thestopper portion is detected and the amount of energization of the shapememory alloy wire is controlled on the basis of detection.
 9. Theactuator according to claim 8, wherein the detection of the state ofabutment is performed by detecting a change in the resistance of anenergization current caused to flow through the shape memory alloy wire.10. An image pickup apparatus comprising: an actuator including a magnetmoved together with a moving portion, a shape memory alloy wire capableof extending and contracting in a direction of movement of the movingportion with execution or non-execution of energization thereof; afixing member attached to a distal end of the shape memory alloy wire, aspring which urges the fixing member toward the magnet along thedirection of movement, and a stopper portion which limits the movementof the magnet along the direction of movement at a set position, whereinthe moving portion is a movable lens frame holding a movable lens, andprovided in a movable lens unit having a magnetic member; a fixed lensframe in which a plurality of objective optical systems are disposed,and in which the movable lens frame is held so as to be able to advanceand retract in a shooting optical axis direction in provided; and theactuator advances and retracts the magnetic member of the movable lensframe by magnetic force from the outside of the fixed lens frame. 11.The image pickup apparatus according to claim 10, wherein the fixed lensframe has an enclosed space closed in a sealing manner at front and rearpositions by the plurality of objective optical systems, and the movablelens unit is disposed in the enclosed space so as to be able to advanceand retreat in the shooting optical axis direction.
 12. An image pickupapparatus comprising: a movable lens unit having a movable lens frameholding a movable lens, and a magnetic member; a fixed lens frame inwhich a plurality of objective optical systems are disposed, and inwhich the movable lens frame is held so as to be able to advance andretract in a shooting optical axis direction; a diaphragm unit whichadjusts the amount of shooting light by moving a diaphragm blade formedof a magnetic material; and a magnet which moves the diaphragm blade bymagnetic force according to the advancement and retraction of themovable lens frame.
 13. The image pickup apparatus according to claim12, further comprising a movable lens drive mechanism which advances andretracts the magnetic member of the movable lens frame by magnetic forcefrom the outside of the fixed lens frame.
 14. The image pickup apparatusaccording to claim 12, wherein the diaphragm unit is disposed in themovable lens frame, and the magnet is disposed on the fixed lens frameand moves the diaphragm blade by magnetic force with the advancement andretraction of the diaphragm unit and the movable lens frame in theoptical axis direction.
 15. The image pickup apparatus according toclaim 12, wherein the diaphragm unit is disposed in the fixed lensframe, and the magnet is disposed on the movable lens frame and movesthe diaphragm blade by magnetic force when advancing and retreating inthe shooting optical axis direction together with the movable lensframe.
 16. The image pickup apparatus according to claim 12, whereineach of the movable lens frame and the fixed lens frame is formed of anonmagnetic material.
 17. The image pickup apparatus according to claim13, wherein the movable lens drive mechanism is an actuator configuredof: a moving magnet which attracts the magnetic member for the movablelens frame; a shape memory alloy wire which contracts and pulls themoving magnet rearward when supplied with electric power; and an urgingmember which urges the moving magnet forward.
 18. The image pickupapparatus according to claim 12, wherein the fixed lens frame has anenclosed space closed in a sealing manner at front and rear positions bythe plurality of objective optical systems, and the movable lens unit isdisposed in the enclosed space so as to be able to advance and retreatin the shooting optical axis direction.